All the demographic and clinical data will be summarized. Factors non related to the coagulation system like catheters, severe infections or congenital heart defects will be recorded. Also a full workup of prothrombotic risk factors are routinely performed in those infants. The study included basic coagulation analysis, Protein C, S and Antithrombin III activity, Activated Protein C Resistance, serum homocystein, lipoprotein (a) and Lupus Anticoagulant.